Nowadays, the liquid crystal display (LCD) is occupying a leading position in the panel display market for its advantageous of small size, low power consumption, small radiation, and the like. In order to display a image on a display panel of LCD, it is necessary to configure a back light unit (BLU) for the display panel. This is because the liquid crystals in the LCD can not emit light by themselves, rather they just regulate the light.
In general, the BLUs may be categorized as side edge backlight modules and direct type backlight modules according to the position of light source therein. The light source in the side edge backlight module is positioned at sides of the display panel, and the light source in the direct type backlight module is positioned at the back of the display panel. The side edge backlight module is widely used in the industry for its advantageous such as low cost, small size and so on.
As shown in FIG. 1, the existing side edge backlight module generally includes a light guide plate (LGP) 1, a light source and an optical module (not shown in FIG. 1), wherein the light source includes a plurality of sub light sources 2 arranged in a line. Wherein, when Light Emitting Diode (LED) is used as the sub light source 2, on one hand, a Hotspot phenomenon occurs (that is, non-uniform luminance) and thus dark regions (black triangle regions in the dot-line circles on the light guide plate 1 as shown in FIG. 1) are generated on the light guide plate 1 due to constraints such as the emitting angle of LED or the like, therefore, in order to assure the uniformity in luminance of the backlight module, a large number of LEDs are used in the light source (for example, in a display device with 14 inch screen, at least forty LEDs horizontally provided on the long side(s) of the light guide plate are necessary), however, though the luminance requirement of the backlight module may be satisfied using a large number of LEDs, the power consumption and cost of the backlight module will be increased. On the other hand, in order to decrease the number of LEDs used, thus to decrease the power consumption and cost of the backlight module, high power LEDs may be used. However, heat may be generated during the operation of the LEDs so that a side of the light guide plate near the LEDs is apt to expand. Especially in a case of using high power LEDs, the expansion will aggravate, and the expanded light guide plate is apt to be in contact with the LEDs, causing a part of the expanded light guide plate at the contact position tend to melt.